Renderbuffer objects were introduced to OpenGL after textures as a possible type of framebuffer attachment, Just like a texture image, a renderbuffer object is an actual buffer e.g. an array of bytes, integers, pixels or whatever. However, a renderbuffer object can not be directly read from.
Quad-buffered Stereo OpenGL To use quad-buffered stereo OpenGL you normally require a 'professional' graphics card that supports it such as NVidia Quadro series, Oxygen's, Wildcats, etc. Many NVidia graphic cards (apart from GeForceFX) can have their Detonator drivers modified by the programme RivaTunerso that quad-buffered stereo is available (if enabled) under Win2000/XP. Quad-buffered OpenGL on nVida Quadro | NVIDIA GeForce Forums May 31, 2010
Apr 03, 2013
LearnOpenGL - Advanced GLSL By specifying greater or less as the depth condition, OpenGL can make the assumption that you'll only write depth values larger or smaller than the fragment's depth value. This way OpenGL is still able to do early depth testing when the depth buffer value is part of the other direction of gl_FragCoord.z.. An example of where we increase the depth value in the fragment shader, but still want to AMD HD3D broken | Community Feb 11, 2015
May 07, 2013
Quad Buffered Stereo Support - Documentation - Unigine To make sure that the Quad Buffered Stereo mode is enabled, check the log file. The Quad Buffer Context should be added to the OpenGL flags string. For example, if you use the NVIDIA Quadro graphics card and run your application on Windows, you should configure the NVIDIA driver as follows: